Police in Florida are investigating the death of an American teenager after he appeared to take an overdose and die while broadcasting on video website Justin.tv.

The 19-year-old left a message on another website in which he described his mental anguish and was encouraged to end his life by a number of other web users.

More than 180 people were watching online as the teenager swallowed pills before collapsing on his bed and appearing to fall unconscious. Only after he stopped moving did some viewers act on what they were seeing by calling the local police to inform them of what was taking place.

The video stream continued to run until police and emergency services arrived at the man's house, with footage showing them entering his bedroom and inspecting the scene before filming stopped abruptly.

In a message posted on bodybuilding.com, the man had described how he felt and explained why he intended to end his life. In response, some other users of the site egged him on.

"You want to kill yourself?" said one. "Do it, do the world a favour and stop wasting our time with your mindless self-pity."

The messageboard on bodybuilding.com where he left the note appears to have been deleted, but many of the comments left in response to it were unsympathetic. Reports also suggest that commenters on the video website itself encouraged him to end his own life.

In response to the news, Justin.tv – a web broadcasting service that allows anybody to create their own live internet television channel – said that it had removed the footage after being alerted to the situation.

In a statement on the company's website, chief executive Michael Siebel made little further comment, merely saying that a "tragedy ... occurred within our community today" and that "we respect the privacy of the broadcaster and his family during this challenging time."